在病例-对照研究中，选择新发病例的优点是（）。 A.需要的样本较小 B.保密性问题较

We sometimes call the lion “the king of the jungle” Because it is stronger and more dangerous than other animals.小题1: It is the highest animal in the land food chain.
In the sea,the shark is one of the animals at the top of the food chain. It can swim faster than most other sea小题2:
小题3:People are! We are not the biggest or fastest.but we are the cleverest. We could not run faster than cheetahs, so we invented cars and now we can move the fastest. We could not fight better than joins. so we invented puns. Now we ran hunt the best-People’s inventions are clever, but they can be dangerous,too.For example, people invented lactones, and now they make the air and rivers dirty. 小题4:Dirty rivers kill fish. hen bears cannot eat the fish and die. If we kill one part of the food chain. other parts also die. Remember that we are a part of the food chain. so we are in danger, too! 小题5: We should and we could do something for the world!

A. Protecting animals is protecting ourselves!

B.And it can use its big teeth to eat them.

C. This can make terrible changes.

D.What is at the top of the world’s food chain?

E. It can run baler than many animals and it ran hunt the best.